1. Technical Field
The present invention relates to linear motors, and more particularly, to a magnet yoke of a linear motor that prevents magnetic flux from excessive saturation for such excessive saturation may counteract magnetic flux at two polarities of a permanent magnet, so as to make a moderate magnetic flux distribution without affecting the output performance of a linear motor.
2. Description of Related Art
Please refer to FIG. 1 through FIG. 3 for a linear motor incorporating a magnet assembly disclosed in U.S. Pat. No. 7,291,953. Therein, a plurality of permanent magnets 2 is arranged in a row on a side surface of a magnet assembly 1 while a plurality of notches 11 are set in equidistance, or in a predetermined distance as described in aforesaid prior-art device, on another side surface of the magnet assembly 1. The center of each said notch is aligned with a corresponding said permanent magnet, and thus each pair of adjacent said permanent magnets 2 interacts with the magnet assembly 1 to generate a magnetic field distribution 3, forming an empty zone 31. The adjacent two empty zones 31 spaced by an interval equal to the interval between each pair of the permanent magnets 2. As such magnetic field distribution 3 passes through two polarities of each permanent magnet 2, it is divided into two circuits forming a magnetic field unit 32. The change of such magnetic field distribution 3 forms an inducing eddy current, which interacts with a shifting magnetic field so as to generate a thrust driving the linear motor to operate in linear motion.
Furthermore, such interval of the empty zone 31 is located in the center of each pair of said permanent magnets 2 and this results in high concentration, or specifically saying “excessive saturation”, of magnetic field distribution 3 over the center of each pair of said permanent magnets 2. Such saturation cancels out the magnetic field distribution 3 flanking two ends of the permanent magnet 2 thereby causing the magnetic fields to distribute unevenly at the flanks of the permanent magnet 2 and in turn weakening the thrust to the linear motor.
Conventionally, the above-mentioned over saturation of the magnetic field distribution 3 would have been solved by using magnetic blocks to realize magnetic guidance.